The proposed research is directed at enhancing the understanding of factors regulating the attachment of gingival fibroblasts (GF) and periodontal ligament cells (PDL cells) to a substratum, in vitro. The attachment of periodontal cells at the healing site is one of the initial requirements for successful tissue regeneration. The specific aims are to determine the biochemical mechanisms regulating the interaction of bone sialoprotein I (BSP I), a known attachment protein, with GF and PDL cell surfaces by: 1) determining the mechanism(s) regulating BSP I persistent attachment effect upon GF.2) determining whether BSP I must bind to bone specific proteoglycans in order to promote cell attachment. 3) identifying the cell receptor(s) for BSP I on GF and PDL cells. 4) determining cell surface distribution of BSP I receptors by preparing antibodies to the BSP I receptors. The studies proposed here will provide important information necessary to achieve the ultimate clinical goal of periodontal regeneration. Moreover, these studies will provide new knowledge on the cellular and molecular biology of human tissue regeneration.